1. Field of the Invention
The present invention relates to an illuminating apparatus and a display panel which are used for a video camera or the like, a view finder and a video camera which use the illuminating apparatus, a video display apparatus, a method of driving the display panel, and the like.
2. Description of the Related Art
A conventional view finder will be first described. In the specification, an element in which at least a light source (light generating means) such as a light emitting device and an image display apparatus (light modulating means) such as a liquid crystal display panel, not of a self light emitting type are integrally formed is called a view finder.
The appearance of a view finder is shown in FIG. 85 as an example. A cross section of the conventional view finder is illustrated in FIG. 86. Shown in the diagrams are the body 851, an eyepiece cover 852, an eyepiece ring 865, and a display panel 863 such as a twist nematic (TN) liquid crystal display panel.
In the body 851, the liquid crystal display panel 863 and a light source 861 such as a backlight are disposed. A magnification lens 866 is disposed in the eyepiece ring 865. By adjusting the degree of insertion of the eyepiece ring 865, the position of the magnification lens 866 can be changed, thereby enabling the focus to be adjusted according to the eyesight of the observer.
The thickness of the liquid crystal layer in the display panel 863 is about 4 to 5 μm. The display panel has a color filter made of a mosaic resin. On both sides of the display panel, polarizers functioning as a polarizer 864a and an analyzer 864b are disposed. The view finder is attached to the video camera body by a mounting fitting 853.
A video system such as a video camera using such a view finder is required to be small and light from the viewpoint of portability and operability, and to be low power consuming. In order to be small and light, since the capacity of a battery which can be mounted is limited, lower power consumption is demanded more and more. Accordingly, in the view finder as well, low power consumption is required. Even when a liquid crystal display panel of lower power consumption is used, if the power consumption of the backlight is large, the power consumption of the whole video equipment is not low.
For example, there is a conventional view finder using a liquid crystal display panel having the effective display area of 0.5 inch, which consumes total 0.7 W in which 0.3 W is consumed by a liquid crystal display and drive circuit and 0.4 W is consumed by the backlight. It is consequently an important subject to reduce the power consumption of an illuminating apparatus as a component of the view finder.
There is also a problem that the size of the conventional backlight 861 is too large to reduce the size and weight of the equipment.
As to the conventional view finder, there is also a problem that a diffuser 862 (refer to FIG. 86) provided to make the backlight a plane light source having little luminance unevenness causes deterioration in the efficiency for light utilization.
More specifically, when a diffuser having a low degree of light diffusion is used, a light emission pattern of a fluorescent tube appears on the display plane of the liquid crystal display panel, which deteriorates the display quality. Although a diffuser whose degree of light diffusion is higher than that of the conventional one is therefore used, generally, the higher the diffusion is, the lower the light transmittance. Consequently, the efficiency for light utilization is lowered.